Regulated rectifier



July 17, 1962 B, w, HOWALD 3,045,170

REGULATED RECTIFIER Filed Jan. 15, 1959 2 Sheets-Sheet 1 INVENTOR. BRIAN W. HOWALD BY QJMW A TTOPNEV July 17, 1962 B. HOWALD 3,045,170

REGULATED RECTIFIER Filed Jan. 15, 1959 2 Sheets-Sheet 2 INVENTOR. BRIAN W. HOWALD A TTOPNEV United States Patent 3,045,170 REGULATED RECTIFIER Brian W. Howald, Amherst, Ohio, assignor to Lorain Products Corporation, a corporation of Ohio Filed Jan. 15, 1959, Ser. No. 786,966 11 Claims. (Cl. 321-49) This invention deals with a regulated rectifying systemand particularly with a system [for controlling a small source of regulated voltage which in turn serves as a standard for controlling the output of a larger system. The invention is an improvement over the arr-angement shown in US. Patent 2,810,876, issued 0ctober 22, 1957, to H. M. Huge and entitled Regulated Rectifier, in which a source of standard voltage is used to control the output voltage of a relatively large rectifying system.

An object of this invention is to provide an improved source of standard voltage for controlling the output or" a regulated rectifying system.

Another object of this invention is to employ a Zener diode for controlling the saturation of a regulating reactor.

Still another object of this invention is to limit the maximum output current of a regulated rectifying system to a specified value by reducing the output of the standard volt-age source whenever the current limit is reached.

A further object of this invention is to operate two or more regulated rectifying systems in parallel and to make them share the load in proportion to their ratings. Another object of this invention is to provide a regulated rectifying system in which the rectified output voltage is substantially independent of the input voltage, the input frequency, the load current, and the ambient temperature.

Other objects and a better understanding of my invention may be obtained by referring to the following specification and claims, together with the accompanying drawings in which:

FIGURE 1 is a schematic diagram of a regulated rectifying system according to this invention, including a standard voltage source comprising a self-saturating transductor biased from a circuit employing a Zener diode.

FIGURE 2 is a schematic diagram of another embodiment of this invention in which the standard voltage source comprises a series connected A.-C. transductor.

With reference to FIGURE 1 there is shown a regulated rectifying arrangement having alternating current input terminals 64 and 65 energized from an alternating current source 10, and having direct current load terminals 2.1 and 22 to which the load 23 is connected. The power circuit extends from the input terminals 64 and 65 through primary winding 66 of the series transformer 25, to the primary 56 of transformer 11. From the secondary winding 26 of the transformer 11 the power circui-t extends through the impedance or gate windings 13 and 14 to the rectifier elements 19 and 20. The positive output terminal 22 is connected to rectifier elements 19 and while the negative output terminal 21 may be connected through compounding winding 68 and filter choke 12 to the center tap of the secondary-winding 26 0t transformer 11.

The circuit as shown thus comprises a choke input type of filter. However, -a capacitor input filter may also be used without substantially "altering the method of control of the regulated rectifying system. The compounding winding 68 will generally be different for capacitor input filterthan for a choke input filter. With the choke input filter as shown, compounding winding 6% is usually phased so that with increasing load current it reduces the saturation of the transductor with which it is associated. That is, the flux set up by winding 68 is opposed to that set up by gate windings 13 and 14. On the other hand for capacitor input filter, not shown, winding 68 is usually phased so it sets up fiux aiding that set up by windings 13 and 14.

The power transductor comprises winding 13 on magnetic core 16 and winding 14 on core =17. The saturating winding 15 which is used to control the saturation of the power transductor is shown here by way of example since other types of transductor construction such as that in which cores 16 and 17 are combined in a single core structure may also be used in the practice of .iy invention.

The saturation of the power transductor is controlled by the control current flowing through saturating winding 15. The current through this winding is produced by balancing the output of a standard voltage source against the voltage across the load terminals 21 and 22.

The standard voltage source in FIGURE 1, comprising cores 35 and 36 with associated windings, rectifiers 37 and 38, and load resistor 30, is an improvement on a similar device shown and described in the previously mentioned US. Patent 2,810,876 which is assigned to the some assignee as this present application. Magnetic core 35 is provided with impedance or gate winding 31 and magnetic core 36 with impedance or gate winding 32 while saturating windings 33 and 34 are common to both cores.

Each or the gate windings 31 and 32 is connected in series with a half wave rectifier element, rectifier 37 being connected with gate winding 31 and rectifier 38 being connected with gate winding 32. Windings 31 and 32 are energized from the center-tapped secondary Winding 27 of transformer 11. Thus rectifier elements 37 and 38 together with winding 27 comprise a full-wave, centertapped circuit having its output voltage under the control of impedance or gate windings 31 and 32.

The cores 35 and 36 are magnetized by a substantially constant bias current fiowing through winding 34. The arrows shown indicate the directions of the direct current fiuxes produced by the various windings on cores 35 and 36. Current through gate windings 31 and 32 demagnetizes the core structure, opposing the premagnetizing effect of the bias current through winding 34. This premagnetization of the core makes the impedance of windings 3'1 and 32 very low for all values of current up to that current which substantially cancels the magnetization produced by winding 31. When this value of current is reached, the impedance of the gate windings becomes very high, limiting the rectified current to a value determined by the premagnetization produced by winding 34. Rectifiers 37 and 38 conduct on alternate half cycles of alternating current, so that each half cycle is limited in the same way, and the resultant rectified current supplied to resistance element 30 is very accurately controlled.

In thisway, a standardized voltage is established across resistor 30. The voltage balancing circuit extends from the resistance element 30 to direct current terminals 21 and 22 through the saturating winding 15, adjusting resistor 24 and saturating winding 33.

The current through saturating winding 33 increases the magnetization of cores 35 and 36 with increasing load current drawn from across resistor 30. This increase of magnetization causes the voltage across resistor 30 to increase as the load current in the voltage balancing circuit increases. The amount of increase is just sufficient to compensate for the voltage drop through winding 33, resistor 24 and saturating winding 15. Because of this characteristic, a substantially constant voltage will be maintained across the load terminals 2 1 and 22 even when substantial amounts of saturating current are termined value.

drawn from the standard voltage source through the saturating winding 15.

In some cases the circuit conditions are such that a reversal of current through winding is required. The current reversing through winding 33 reduces the premagnetization of cores 35 and 36 at exactly the rate required to maintain constant voltage across terminals 21 and 22. Reverse current is limited to an amount somewhat less than that required to produce the standard voltage across resistor 36. This limits the reverse current through winding 15 and prevents excessive reverse magnetization of the power transductor, a condition which could cause loss of control of the voltage across terminals 21 and 22.

The regulated biasing circuit for winding 34 is basically a constant voltage source. The primary element in the biasing circuit is a semiconductor diode 2 operated in the breakdown region, where it has a substantially constant voltage characteristic. The diode 42 is a device known in the art as a Zener diode, but other constant voltage devices such as a gas discharge tube may be utilized.

The Zener diode 42 is energized from the full wave rectifier 32 through the current limiting resistor 46. Power is supplied to rectifier 39 from an isolated secondary winding 2d of transformer 11 and a capacitor 41 is connected across the D.-C. terminals of rectifier 32 to filter the rectified voltage. The bias current path for energizing winding 34 is from the Zener diode 42 through resistors and 54 and through diode 46. Resistor 54 is the main current limiting resistor and its resistance should preferably be much greater than the resistance of winding 34 in order that temperature changes have no substantial effect upon the circuit constants. Alternatively, resistor 54 may have a negative temperature coefiicient to compensate for changes in the resistance of winding 34 with changing ambient temperature.

Whenever the voltage of source 10 increases, the standard voltage has a tendency to rise slightly. in order to counteract this slight rise in voltage, the bias current supplied to winding 34 may be decreased at a rate sufficient to maintain a constant output voltage in the standard voltage source. This reduction of bias current with increasing input voltage is accomplished by subtracting from the voltage across Zener diode 42 a small voltage which increases with increasing line voltage. The subtractive voltage is developed across resistor 45 and is supplied from rectifier 43 which is connected to winding 29 of transformer 11. Variable resistor 44 is connected in series with resistor 45 to provide an adjustment for the correction voltage. A smoothing element such as capacitor 69 may also be used to filter the rectifiedoutput of rectifier 43.

The circuit just described is capable of maintaining a standardized voltage across the resistor 34?, which in turn, through the voltage balancing circuit, is capable of main-' taining a constant voltage across output terminals 21 and 22. Any changes in the saturation of cores 16 and 17 required to maintain the constant output voltage are produced by changes in the saturating current through winding 15 as previously described.

Capacitor 18 is shown connected across winding 15 to minimize ripple voltage in the VOlla G balancing circuit. Other filtering arrangements known in the art may also be used for preventing ripple voltage in the saturating winding 15 from feeding back into rectifiers 37 and 38.

Another feature of my invention is a current limiting circuit whereby the maximum load current which can be drawn from terminals 21 and 22 is limited to a prede- The current limiting circuit comprises transformer 25 having primary winding 66 connected in series in the A.-C. power circuit. Secondary winding 67 of transformer 25 is connected to rectifier 47 which has a resistor 49 connected across its direct current terminals. Transformer 25 acts as a current transformer, producing a voltage across resistor 49 substantially proportional to the output current delivered from load terminals 21 and 22. Filter capacitor 48 connected in parallel with resistor d9 smooths the rectified voltage so that it can be balanced against the constant voltage developed across resistor 54. The voltage is balanced through the diode 52 which maintains a substantially open circuit as long as the rectified voltage across resistor 49 is less than that across resistor 54.

Resistor 49 is adjustable by means of slider 51 to facilitate adjustment of the rectified voltage, so that a balance point is reached at a predetermined value of load current. For load currents greater than this predetermined value, the voltage across resistor 49 is greater than the voltage across resistor 54 and diode 52 conducts, passing added current through resistor 54 to increase the voltage across this resistor. Any increase in load current beyond the value required to cause diode 52 to conduct will increase the voltage across resistor 54 and reduce the bias current through winding 34. As a result, the standard voltage is reduced, and the output voltage across terminals 21 and 22 is reduced correspondingly. Diode 46 is included in the biasing circuit to insure that the bias current will not reverse in case the resistance of load 23 is reduced to a very low value. Capacitor 53 may also be used as shown, in parallel with resistor 54 to minimize ripple voltage which could be rectified by diode 52, and thus would make this diode conduct even though the voltage across resistor 49 is less than that across resistor 54. By use of capacitor 53 the undesirable function is eliminated.

The voltage developed across a portion of resistor 49 may also be used for synchronizing the outputs of two or more similar regulated rectifying systems. This is accomplished by connecting one end of resistor 49 to the positive output terminal 22 through the regulating resistor 24. A slider on resistor 49 is connected to a separate paralleling terminal 55. When two or more regulated rectifying systems of the type shown are operated in parallel, the corresponding terminals 55 in the several systems are connected together to establish a synchronizing circuit associated with resistor 49.

As long as each of the parallel rectifiers is carrying its proportional share of the load, the voltages in the synchronizing circuit will be equal. However, in case one rectifier delivers less than its share of current, the voltage across its resistor 49 will be less than that in the other units carrying more than their share of the load. A circulating current will, therefore, flow from terminal 22 through resistor 24 and resistor 49 to terminal 55 in the unit delivering less than its share of the load. Since re sistor 24 is in the voltage balancing circuit which extends from resistor 30 to the load terminals 21 and 22, the circulating current flowing through resistor 24 has the same effect on this circuit as a reduction in voltage across terminals 21 and 22. An increased saturating current is thereby caused to fiow through winding 15 to increase the voltage across terminals 21 and 22, and to increase the output current of the rectifier which had been carrying less than its share of the load. An opposite effect is I experienced in the rectifiers operating in parallel. The

action of the paralleling circuit shown in FIGURE 1 is similar to that of the paralleling circuit shown in U.S. Patent 2,810,876, previously mentioned.

FIGURE 2 is the schematic diagram of another embodiment of my invention with a modified standard voltage circuit. The power circuit in FIGURE 2 is substantially the same as in FIGURE 1, extending from the alternating current input terminals 64 and 65 through primary winding 56 and secondary Winding 26 of power transformer 11, gate windings 13 and 14 and rectifying elements 19 and 20 to positive output terminal 22. Negative output terminal 21 is connected through filter choke 12 to the center tap of secondary winding 26. The compounding winding 68 shown in FIGURE 1 has been omitted in FIGURE 2, since it is an optional feature as described in connection with FIGURE 1.

In FIGURE 2, the self-saturating reactor circuit shown in FIGURE 1 and comprising rectifying elements 37 and 38 is replaced by an A.-C transductor circuit employing gate windings 31a and 32a and full wave rectifier 58. Gate winding 31a is on core 35 and gate winding 32a is on core 36 as in FIGURE 1. These two cores are biased by a substantially constant current impressed on Winding 34a as in FIGURE 1. The biasing circuit of FIGURE 2 has been modified by the omission of one of the rectifiers shown in FIGURE 1. The compensating voltage developed across resistor 45 in FIGURE 1 is obtained across a portion of resistor 59 terminated at slider 60 in FIGURE 2. With the circuit of FIGURE 2, the rectifier 39 which energizes the constant voltage device 42 also supplies the compensating voltage supplied by rectifier 43 in FIGURE 1. The compensating voltage is subtracted from the voltage across the constant voltage device 42 to adjust the bias through winding 34 with changing input voltage in the amount required to maintain constant voltage across load terminals 21 and 22.

The substantially constant premagnetization of cores 35 and 36 makes the impedance of gate windings 31a and 32a very low for values of load current less than the value required to demagnetize one of the cores. Windings 31a and 32a are polarized so that while the current through one of them is aiding the premagnetization of its core, the current through the other winding is opposing the premagnetization of its core. Therefore, on each half cycle, one of the cores attains a very high impedance at the current at which it produces a magnetizing force equal and opposite to the magnetizing force produced by the bias windings. The current supplied to rectifier 58 is thus closely regulated in the same way that the current supplied through rectificrs 37 and 38 was regulated in FIGURE 1. The regulated current, being rectified by rectifier 58, passes through resistor 30 to produce a standard D.-C. voltage. Capacitor 57 is shown in FIG- URE 2 as a filtering element together with inductance 61 and resistor 63. Resistor 63 takes the place of capacitor 18 shown in FIGURE 1 in minimizing ripple voltage across saturating winding 15. Inductance 61 and capacitor 57 further insure that ripple voltage from winding 15 or from output terminals 21 and 22 will not be impressed on rectifier 58.

The voltage balancing circuit in FIGURE 2 extends from resistor 30 through'compounding winding 33, adjusting resistor 24, and saturating winding 15 as in FIG- URE 1. As previously mentioned, this circuit also includes inductance 61 in FIGURE 2. The action of the compounding winding on the standard voltage source in FIGURE 2 is the same as in FIGURE 1, as was previously described.

The synchronizing circuit terminating at terminal 55 in FIGURE 2 is also substantially the same as the synchronizing circuit in FIGURE 1.

The current limiting feature in FIGURE 2 comprising transformer 25, rectifier 47, resistor 49 and diode 52 operates to reduce the bias current through winding 34 whenever the load current exceeds a predetermined value, as already described in connection with FIGURE 1.

Although I have described my invention with a certain degree of particularity as applied to a. single-phase centertapped rectifying system, it is understood that this disclosure has been made only by way of example, and that the principles of my invention may be practiced in various modifications which will be apparent to those skilled in the art. For example, particularly, the standard voltage source of my invention may be used in other types of voltage regulating systems, and other changes in the details of construction in the combination and arrangement of parts may be resorted to without departing from the spirit and the scope of the invention as hereinafter claimed.

What I claim is:

l. A regulated rectifying system having alternating current input terminals and direct current load terminals and comprising in combination, first rectifying means and first saturable reactor means serially connected between said input and said output terminals, first saturating wind ing means for controlling the saturation of said first saturable reactor means, second saturable reactor means, second rectifying means, first resistor means, first circuit means for energizing said first resistor means from said input terminals through said second saturable reactor means and said second rectifying means, second saturating winding means for controlling the saturation of said second saturable reactor means, a constant voltage device, means for supplying direct current to said device, second resistor means, second circuit means for supplying current to a portion of said second saturating winding means from said constant voltage device through said second resistor means, third rectifying means, means for energizing said third rectifying means in accordance with the load current delivered from said load terminals, fourth rectifying means, third circuit means extending from said third rectifying means through ,said fourth rectifying means to said second resistor means for reducing the current in said second circuit means when said load current exceeds a predetermined value, and fourth circuit means extending from said first resistor means through said first saturating winding means and a portion of said second saturating winding means to said load terminals for controlling the voltage across said terminals.

2. A regulating arrangement having an alternating current input and a direct current output comprising in combination, first rectifying means, first magnetic core means having first impedance winding means and first saturating Winding means thereon, a first circuit extending from the input to the output and including said first impedance winding means and said first rectifying means in series, second rectifying means, second magnetic core means having a second impedance winding means and second saturating winding means thereon, a first resistance ele ment, circuit means for connecting said first saturating winding means and said second saturating winding means in series with said first resistance element, a second circuit extending from said second rectifying means in series with said second impedance winding means, a third circuit extending from said first resistance element to said direct current output and including at least a portion of each of the said first and second saturating winding means to control the impedance of the first impedance winding means in response to the difference between the voltage across said first resistance element and the direct current output voltage, means for energizing a portion of said second saturating winding means with a substantially constant direct current, said means comprising a constant voltage device, a second and third resistance element, and a third, rectifying means, means for connecting said constant voltage device in series with said second resistance, means for energizing said constant voltage device element through said third rectifying means from said alternating current input, said constant voltage device being serially connected with a portion of said second saturating winding means and said third resistance element.

3. A regulating arrangement having an alternating current input and a direct current output comprising in combination, first rectifying means, first magnetic core means having first impedance winding means and first saturating winding means thereon, a first circuit extending from the input to the output and including said first impedance winding means and said first rectifying means in series, second rectifying means, second magnetic core means having a second impedance winding means and second saturating winding means thereon, a first resistance element, circuit means for connecting said first saturating winding means and said second saturating winding means in series with said first resistance element, a second circuit extending from said second rectifying means in series with said second impedance winding means, a third circuit extending from said first resistance element to said direct current output and including at least a portion of each of the said first and second saturating winding means to control the impedance of the first impedance winding means in response to the difference between the voltage across said first resistance element. and the direct current output voltage, means for energizing a portion of said second saturating Winding with a substantially constant direct current, said means comprising a constant voltage device, second, third and fourth resistance elements and third and fourth rectifying means, said constant voltage device being connected in series with said second resistance element and being energized through said third rectifying means from said alternating current input, said constant voltage device being serially connected with a portion of said second saturating Winding means and said third and fourth resistance elements, means for connecting said fourth resistance element in parallel with said fourth rectifying means and means for energizing said fourth rectifying means from said alternating current input.

4. A regulating arrangement having an alternating cur rent input and a direct current output comprising, in combination, first rectifying means, first magnetic core means having first impedance winding means and first saturating means thereon, series transformer means, a first circuit extending from said input to said output and including said series transformer means, said first rectifying means and said first impedance winding means in series, second rectifying means, second magnetic core means having second impedance winding means and a second saturating winding means, a first resistance element, a second circuit extending from said input to said resistance element and including said second rectifying means in series with said second impedance winding means, a third circuit extending from said first resistance element to said load and including at least a portion of each of said first and second saturating winding means, means for supplying a substantially constant direct current to said second saturating winding means, said means comprising a constant voltage device, second, third, and fourth resistance elements and third, fourth, fifth and sixth rectifying means, means for connecting said constant voltage device in series with said second resistance element and means for energizing said constant voltage device through said third rectifying means from said alternating current input, said constant voltage device being serially connected with a portion of said second saturating winding, said third and said fourth resistance elements, said fourth resistance element being connected in parallel with said fourth rectifying means energized from said alternating current input, and means for energizing said fifth rectifying means from said series transformer means, said fifth rectifying means being connected in series with said third resistance element and said sixth rectifying means.

5. A regulating arrangement having an alternating current input and direct current output comprising, in combination, first rectifying means, first magnetic core means having first impedance winding means and first saturating means thereon, series transformer means, a first circuit extending from the input to the output and including said series transformer means, said first rectifying means and said first impedance winding means in series, second rectifying means, second magnetic core means having second impedance winding means and a second saturating winding means, a first resistance element, a second circuit extending from said input to said resistance elemnet and including said second rectifying means in series with said second impedance winding means, a third circuit extending from said first resistance element to said load and including at least a portion of each of said first and second saturating Winding means, means for supplying a substantially constant direct current to said second saturating winding means, said means comprising a constant voltage device, second, third, fourth, and fifth resistance elements, and third, fourth, fifth, sixth, and seventh rectifying means, said constant voltage device being connected in series with said second resistance element and energized through said third rectifying means from said alternating current input, said constant voltage device being serially connected with a portion of said second saturating winding means, said third and fourth resistance elements and said fourth rectifying means, said fourth resistance element being connected in parallel with said fifth rectifying means energized from said alternating current input, means for energizing said sixth rectifying means from said series transformer means, and means for connecting said sixth rectifying means in series with said third resistance element and said seventh rectifying means and means for connecting said fifth resistance element in parallel with said sixth rectifying means.

6. A regulating arrangement having an alternating current input and a direct current output comprising, in com bination, first rectifying means, first magnetic core means having first impedance winding means and first saturating Winding means thereon, a first circuit extending from said input to said output and including said first impedance Winding means and said first rectifying means in series, second rectifying means, second magnetic core means having a second impedance winding means and second saturating winding means thereon, a first resistance element, circuit means for connecting said first saturating winding means and said second saturating winding means in series with said first resistance element, a second circuit extending from said second rectifying means in series with said second impedance winding means, a third circuit extending from said first resistance element to said direct current output and including at least a portion of each of the said first and second saturating winding means to control the impedance of the first impedance winding means in response to the difference between the voltage across said first resistance element and the direct current output voltage, means for energizing a portion of said second saturating Winding with a substantially constant direct current, said means comprising a Zener diode element, second, third, and fourth resistance elements, and third rectifying means, means for connecting said Zener diode element in series with said second resistance element and means for energizing said Zener diode element through said third rectifying means from said alternating current input, said third resistance element being connected in parallel with said third rectifying means, and means for serially connecting said Zener diode element with a portion of said second saturating winding means, said fourth resistance element and a portion of said third resistance element.

7. A regulating arrangement having an alternating current input and a direct current output comprising in combination first rectifying means, first magnetic core means having first impedance Winding means and first saturating means thereon, a series transformer, a first circuit extending from the input to the Output and including said series transformer, the first rectifying means and the first impedance winding means in series, second rectifying means, second magnetic core means having second impedance winding means and a second saturating winding means thereon, a first resistance element, a second circuit extending from said input to said resistance element and including said second rectifying means in series with said second impedance winding means, a third circuit extending from said first resistance element to said direct cur rent output and including at least a portion of each of said first and second saturating winding means, means for supplying a substantially constant direct current to said second saturating winding means, said means comprising a Zener diode element, second, third, and fourth resistance elements and third, fourth, and fifth rectifying means, means for connecting said Zener diode in series with said second resistance element, means for energizing said Zener diode through said third rectifying means from said alternating current input, means for connecting said third resistance element in parallel with said third rectifying means, said Zener diode element being serially connected with a portion of said second saturating Winding, said fourth resistance element and a portion of said third resistance element, means for energizing said fourth rectifying means from said series transformer and means for connecting said fourth rectifying means in series with said fourth resistance element and said fifth rectifying means.

8. A regulating arrangement having an alternating current input and a direct current output comprising, in combination, first rectifying means, first magnetic core means having first impedance winding means and first saturating means thereon, a series transformer, a first circuit extending from the input to the output and including said series transformer, said first rectifying means and said firstimpedance winding means in series, second rectifying means, second magnetic core means having second impedance winding means and a second saturating winding means, a first resistance element, a second circuit extending from said input to said resistance element and including said second rectifying means in series with said second impedance winding means, a third circuit extending from said first resistance element to said direct current output and including at least a portion of each of said first and second saturating winding means, means for supplying a substantially constant direct current to said second saturating winding means, said means comprising a Zener diode element, second, third, and fourth re sistance elements, and third, fourth, fifth, and sixth rectifying means, means for connecting said Zener diode element in series with said second resistance element and means for energizing said Zener diode element through said third rectifying means from said alternating current input, means for connecting said third resistance element in parallel with said third rectifying means, said Zener diode element being serially connected with a portion of said second saturating winding, said fourth resistance element, said fourth rectifying means and a portion of said third resistance element, means for energizing said fifth rectifying means from said series transformer and means for connecting said fifth rectifying means in series with said fourth resistance element and said sixth rectifying means.

9. In a regulating rectifier, in combination, an alternating current input and a direct current output, a power circuit connecting said input and output and including a power transductor and a rectifier, said power transductor including gate windings and a saturating winding, means for connecting said gate windings between said input and said output through said rectifier, a standard voltage source including a second rectifier, a load resistor and a control transductor energized from said alternating current input, said control transductor having impedance windings and a saturating winding, means for connecting said impedance windings between said alternating current input and said second rectifier to control the output voltage of said standard voltage source, means for connecting said load resistor, said power transductor saturating winding and a portion of said control transductor saturating winding in series through said direct current output, a constant bias pre-magnetizing current source including a constant voltage device and a portion of said control transductor saturating winding and means for energizing said premagnetizing current source from said alternating current input.

10. In a regulating rectifier, in combination, an alterne ting current input and a direct current output, a power circuit connecting said input and output and including a power transductor and a rectifier,v said power transductor including gate windings and a saturating winding, means for connecting said gate windings between said input and said output through said rectifier, a standard voltage source including a second rectifier, a load resistor and a control transductor energized from said alternating current input, said control transductor having impedance windings and a saturating winding, means for connecting said impedance winding between said alternating current input and said second rectifier to control the output voltage of said standard voltage source, means for connecting said load resistor, said power transductor saturating winding and a portion of said control transductor saturating winding in series through said direct current output, a constant bias premagnetizing current source including a constant voltage device, a portion of said control transductor saturating winding and a first resistor, a current transformer energized by said alternating current input, a rectifier across the output of said current transformer, and in turn energizing said first resistor, a second resistor across the output of said rectifier, an electrically unidirectional device, said first resistor and said second resistor being connected by said electrically unidirectional device, said device being arranged to maintain a substantially open circuit between the resistors when the voltage across the first resistor exceeds that across the second resistor and to conduct when the voltage across the second resistor exceeds that across the first resistor whereby the standard voltage is reduced upon increase in load current beyond a predetermined overload value.

11. In a regulating rectifier, in combination, an alternating current input and a direct current output, first rectifying means serially connected between said input and said output for supplying said output, transductor means for controlling the current through said first rectifying means, second rectifying means, said transductor means having gate winding means and control winding means including saturating winding means and bias winding means, means for connecting said saturating winding means serially to said gate winding means through second said rectifier, a biasing circuit for biasing said transductor means, said biasing circuit comprising a constant voltage device, said bias winding means on said transductor means and first and second resistance means, means for electro-magnetically coupling said bias winding means to said gate winding means, means for impressing on said first resistance means a unidirectional voltage varying with source voltage, means for impressing on said second resistance means a unidirectional voltage dependent upon the load current through said rectifying means when said current exceeds a predetermined value whereby the bias supplied to said transductor means is reduced by increase in source voltage impressed on said first resistance means and is further reduced by increase in load current above the predetermined value impressed on said second resistance means.

References Cited in the file of this patent UNITED STATES PATENTS 2,019,3'52 Livingston Oct. 29, 1935 2,774,930 Bixby Dec. 18, 1956 2,798,571 Schaelchlin et a1. July 9, 1957 2,914,720 Merkel Nov. 24, 1959 2,937,328 Huge et al. May 17, 1960 

